Dengue fever is a viral disease transmitted by mosquitoes that is widespread in tropical and subtropical areas globally. It is caused by four closely related dengue virus serotypes (DEN-1, DEN-2, DEN-3, and DEN-4) and primarily transmitted to humans through the bite of infected female Aedes mosquitoes, specifically Aedes aegypti. This disease has become a significant concern for global health, with an increasing number of cases and geographic expansion in recent decades.
Historically, the first documented outbreaks of illnesses resembling dengue can be traced back to the 18th century in Asia, Africa, and the Americas. However, the first detailed description of dengue fever was provided by Benjamin Rush in 1789 during an outbreak in Philadelphia, USA. The name "dengue" originates from the Spanish phrase "dengue" or "denga," which means "fastidious" or "careful," describing the characteristic way in which patients would walk bent over due to severe joint pain.
Dengue is prevalent in more than 100 countries, primarily in tropical and subtropical regions of Asia, Africa, the Americas, and the Pacific. According to the World Health Organization (WHO), approximately 3.9 billion people worldwide are at risk of dengue infection, and an estimated 390 million cases occur annually. However, the precise number of cases is difficult to determine due to underreporting and misdiagnosis.
The main mode of dengue transmission is through the bite of the Aedes mosquito. Aedes aegypti is the primary vector for dengue and is commonly found in urban and semi-urban areas, breeding in water-filled containers near human settlements. Another mosquito species, Aedes albopictus, can also transmit the virus and is more prevalent in rural and suburban regions, contributing to the spread of dengue.
Key risk factors for dengue transmission include:
1. Inadequate mosquito control: Insufficient methods for controlling mosquitoes and poor sanitation practices can lead to an increase in mosquito breeding sites and higher rates of dengue transmission.
2. Urbanization and population growth: Rapid urbanization often results in larger populations living in close proximity to Aedes mosquito breeding sites, facilitating the spread of the disease.
3. Climate change: Environmental factors, such as temperature and rainfall patterns, can affect the distribution and abundance of mosquitoes, consequently influencing the incidence of dengue.
4. Travel and globalization: International travel can transport infected individuals to regions where dengue is not endemic, resulting in localized outbreaks.
5. Socioeconomic factors: Factors such as poverty, overcrowding, and limited access to healthcare can increase the risk of dengue transmission and the severity of the disease.
The impact of dengue varies across regions and populations. The highest burden of dengue is observed in Southeast Asia and the Western Pacific, where nearly 75% of global cases occur. Nevertheless, the disease has rapidly spread to other regions, including the Americas, Africa, and the Eastern Mediterranean. In recent years, dengue outbreaks have also been reported in regions with previously low prevalence, such as Europe and the United States.
Certain populations, including infants, young children, and pregnant women, are more susceptible to severe dengue infection. Individuals with pre-existing medical conditions, such as diabetes or asthma, may also have a higher risk of experiencing severe symptoms. Additionally, factors like age, immunity, and genetic predisposition can influence the severity and outcome of dengue infection.
In conclusion, dengue represents a significant global health issue with a high prevalence in tropical and subtropical regions. The primary mode of transmission is through the bite of infected Aedes mosquitoes, and risk factors include inadequate mosquito control, urbanization, climate change, travel, and socioeconomic conditions. The impact of dengue varies across regions and populations, with Southeast Asia and the Western Pacific being the most affected. Efforts to control dengue involve measures to control mosquito populations, engagement of communities, and the development of a dengue vaccine.

Download Data(下载数据)

Seasonal Patterns:
Analysis of the data provided reveals distinct seasonal patterns in the incidences of Dengue in mainland China. Specifically, the number of cases shows a consistent increase from June to September, aligning with the summer season. This correlation can be attributed to the mosquito-borne nature of dengue, as mosquitoes tend to be more active in warmer temperatures. Conversely, during the winter months (December to February), a significant decrease in the number of cases is observed.
Peak and Trough Periods:
In mainland China, the peak period for Dengue cases is typically observed in September, when the number of cases reaches its highest point due to heightened mosquito activity amidst the warm and humid summer climate. Conversely, the trough period, characterized by the lowest number of cases, occurs during the winter months from December to February.
Overall Trends:
Upon examining the overall trend of Dengue cases in mainland China, it becomes apparent that fluctuations occur over the years, with some years experiencing higher case numbers than others. From 2010 to 2014, there was a progressive increase in the number of cases, reaching a peak in 2014. However, a gradual decrease has been observed since 2015, although occasional fluctuations persist. It is crucial to exercise caution while interpreting the data, as negative values are occasionally encountered for certain months, implying potential errors in data recording or reporting.
Discussion:
The provided data strongly suggests the presence of seasonal patterns in Dengue cases within mainland China, with higher numbers occurring during summer months and lower numbers during the winter. The peak period for cases is consistently observed in September, with the trough period aligning with the winter months. Furthermore, an overall downward trend in cases is evident from 2015 onwards, although sporadic fluctuations continue to arise. However, it should be noted that the accuracy of the data might be impacted by inconsistencies in reporting, as evidenced by instances of negative case values. Therefore, further analysis and investigation are necessary to comprehensively comprehend and interpret the observed patterns and trends.